I'm still dithering on ordering a cuben tarp shelter. In the meantime I picked up a 1.43oz cuben fiber stake sack from Joe at ZPacks.com. I have not seen cuben in person before.

Holy smokes Batman! Very light, quite well made... but if this 1.43oz cuben, it is hard to imagine a strong shelter made from 0.74oz or even 0.51oz cuben. I'm not saying its impossible, obviously some very adept outdoorspeople use those fabrics with great success. I'm just gobsmacked at how wispy the stuff is.

I understand UL gear requires greater care than bombproof stuff. It's going to take a mental adjustment for me to feel confident in a cuben tarp. Ya gotta pay to play...

I just got my zpacks hexamid solo a few hours ago and have it spread out on the floor. Go for it. This thing is a dream I hope never to wake from.

My previous experience with cuben is Joe's pack covers which seem like they are of a similar weight. The fabric is extremely strong, although I have a few tiny punctures in my pack cover, probably from scrambling through evil brush, which mend quite well with duct tape. I don't intend to scramble through brush while in the hexamid. The fabric does not sag like silnylon. Checking out now to put the guylines on and seam seal it....

Funny, your post reads a little like one I put up a couple years ago after looking at a sample of the 1/3 ounce version of cuben Quest Outfitters sent me.

You might want to take a look at Richard Nisley's fairly recent long threads on the MYOG and GEAR forums on this site, wherein he tested many samples of cuben and silnylon for water resistance.

Since then he has posted more than once that cuben fiber material with the .18 suffix has more substantial and water resistant layers of mylar (the stuff that looks like cellophane) encapsulating the fibers than does the material with the .08 suffix. If you can obtain cuben of the desired weight with the .18 suffix, you will, if nothing else, feel better about the durability of your equipment. After reading Richard's threads, you can draw your own conclusions about actual durability and water resistance.

A number of us purchased cuben prior to Richard's reports, but are making the best use of cuben with the thinner mylar. It's way too expensive for many to discard, and is as water resistant as a lot (but not all) of the silnylon currently available; and in the opinion of many is quite serviceable, and clearly, does not sag like thin silnylon when its surface temperature drops (note posts above). Forgive me, but this topic has been raised on so many threads here, that I have become too lazy to look up the links yet once again. But hope the above will help to get you started if you want to delve into the subject. Just use the BPL search feature.

FYI, my own decision, adopting the suggestion of another poster, was to use my 3/4 ounce cuben with the .08 suffix for tent end covers (the portion of the canopy that covers the vestibule(s), but not the sleeping area) of a tent. (This raises the sticky question of how to best join cuben to other materials.) Many others have reported quite satisfactory results with cuben tarps made entirely of the thinner mylar cuben, with reinforcements at stress areas as found on most backpacking shelters. As of yet, I have not completed the project and put the end covers to frightful weather, so have no strong opinions either way. I am confident enough about the material, however, to put in the hours making the tent. Ironically, from all reports, it is made of a better quality (but not thicker) mylar material that may have been sent to me through an oversight. Time will tell, and hopefully, BPL and I will still be here to post the results.

I personally am very happy with a 0.08 mylar cuben for a tarp or tent fly application where the actual amount of abrasion/abuse is very low. Tons of people have been using cuben in this application for years now and I've never heard of anyone having a waterproofing issue in the field. For a floor (or other applications like a food sack, stake sack etc) then you want a .18 cuben for the added durability.

I personally prefer 0.74oz cuben for tarp/tent fly applications, but a 0.51oz cuben would easily work if you're the product is well designed and you're willing to be a little more careful with it. The 0.33 stuff is too sketchy for a tarp IMO, but I do use it for a large clothing sack and that's held up for 2 years now with no damage.

I made a dry bag of .74 breen cuben about a year ago. It was fully waterproof at first and then a test found a few pin holes that I sealed easily with Aquaseal. It is now so full of tiny holes that I do not want to seal any more up. Some spectra threads have pulled which leaves a line of potential holes. I have my doubts that cuben is the material for dry bags. It is still strong and as a tent that sheds water by its shape it might well still be useable.

Thought I would post this quick message with a link to my 0.34 cuben fiber tarp for anybody wondering what pushing the extreme of CF involves.

It just started raining here in the Redwoods so the tarp is going to be getting some wet weather testing very soon and I will keep uploading new videos of it as I continue to perform endurance testing on the 0.34 cuben fiber.